ICD-11 classes
21 Symptoms, signs or clinical findings, not elsewhere...
Mental or behavioural symptoms, signs or clinical findings
MB24 — Symptoms or signs involving mood or affect
MB24.6 — Disturbance of affect
MB24.62 — Flat affect

ICD-11 MB24.62 — Flat affect

Absence or near absence of any sign of affective expression.

The diagnosis includes nothing.

The diagnosis excludes nothing.

It has no clarifying diagnoses.